A method and system for communicating among clients in a client-server computer network. The method and system allow a client to identify another client using a first identifier, such as a domain name of the other client. It is not necessary for the client to identify the other client with its network address, such as the Internet protocol (IP) address of the other client. The system comprises a server that updates a domain name system (DNS) server with the most recent IP address of the other client. In the event that the other client is off-line, the client may be connected to a Web page of the other client to leave and retrieve messages.